1. Field of the Invention
The present invention relates to a data transfer method and an image formation system.
2. Related Background Art
Conventionally, an image processing system in which an image formation apparatus and an image reading apparatus are connected to an image processing controller having a command interface for transferring and receiving commands with a PDL (page-description language) controller and a video interface for transferring and receiving image data with the PDL controller is used.
In the PDL controller, PDL data received from a host computer connected thereto through a network or the like and described by a page-description language is first analyzed, and the analyzed data is expanded into raster image data. Then, a command sequence constructed based on the analyzed result is transferred to the image processing controller through the command interface, and thereafter the image data is transferred thereto through the video interface.
On one hand, in the image processing controller, an image formation unit is activated based on the command sequence and the image data both received from the PDL controller, an image represented by the received image data is formed on a recording sheet (paper), and the recording sheet on which the image has been formed is discharged outward.
Incidentally, an image formation unit (printer) which forms images of four colors, i.e., Y (yellow), M (magenta), C (cyan) and K (black), respectively on an image bearing body is equipped with one video data signal line. Thus, in a case where the image data of the four colors are transferred from an image generation controller unit to an image processing controller unit, the image data of each color completely occupies the video data signal line while this data is being transferred.
On one hand, an image formation unit (printer) which forms images of the four colors Y, M, C and K respectively on four image bearing bodies is equipped with four video data signal lines, whereby the image data of the four colors are simultaneously transferred from an image generation controller unit to an image processing controller unit. However, in this image formation unit, when only the data corresponding to the K image is transferred, this data is transferred by only one video data signal line in the same manner as above. That is, the remaining three video data signal lines are not used in this case.
However, in the above conventional image processing system, the number of the video data signal lines to be used when the image data are transferred between the image generation controller unit and the image processing controller unit is determined based on the number of the image bearing bodies provided in the image formation unit.
That is, the number of the video data signal lines and data transfer control between the image generation controller unit and the image processing controller unit must be changed according to the number of the image bearing bodies provided in the image formation unit.
Moreover, in the image processing system which is equipped with the four video data signal lines, even if the image data transferred from the image generation controller unit is only the data corresponding to the K image, only one video data signal line is used and the remaining three video data signal lines are not used, whereby the image data transfer is not effectively processed